Add tests for federated SPARQL queries between the curies mapping service and popular triplestores

[vemonet]

Add tests to check if federated queries between the curies mapping service and popular triplestores properly work.

Triplestores need to be deployed locally before running the tests with docker compose, if the triplestores are not deployed the tests for federated queries will be skipped

Added:

• a docker-compose.yml to deploy the bioregistry, blazegraph and virtuoso
• a resources/ folder in tests which contains the Dockerfile for the curies mapping service used for testing, and an init script for the triplestores
• a step to start and init the triplestores in the gh action for testing
• instructions to start the triplestores with docker compose in the readme
• a tests/test_sparql.py file with 4 tests of federated queries using SERVICE: from virtuoso to curies, from blazegraph to curies, from curies to virtuoso, from curies to blazegraph